Re: [PROPOSAL] Termination of Background Workers for ALTER/DROP DATABASE

On Thu, Oct 09, 2025 at 04:00:24AM +0000, Hayato Kuroda (Fujitsu) wrote:
> Based on that, I imagined that we could launch a bgworker and create
> another database by using template. Or is it already handled?

Oh, I was not following you here. Yes, we should have something with
a bgworker connected to a source and make sure that it disconnects
when create a new database with this source as template.

However, could there be more to consider here? Contrary to DROP
DATABASE, where we require the drop to be done by the owner of the
database (or a superuser), CREATE DATABASE has less requirements: it
is fine for a role to create a database if they have the CREATEDB
rights. If we allow bgworkers to be cancelled when the database they
are connected to is used as a source, that may be disruptive, so we
had better document precisely the behavior of the flag and what users
should expect from it when set. We are already killing autovacuum
workers when they are connected to a database used as a source anyway
(since 4abd7b49f1e9 from 2008), so I am worrying for nothing and it is
actually better to apply the same rule across the board. Let's just
document very clearly how the bgworker will react when the cancel flag
is set in all these cases.
--
Michael